Method and system for determining road traffic jams based on information derived from a PLMN

ABSTRACT

A method of estimating traffic jams on a roads network includes receiving information from at least one cellular PLMN covering a geographic region wherein at least one road of the roads network to be monitored is located. The information includes data related to call traffic handled by the cellular PLMN in an at least one area of the geographic region, and an indication related to a mobility of mobile terminals into/out of the area. The method may further include providing an indication of traffic jam in the at least one road in case the call traffic handled by the cellular PLMN in the at least one area exceeds a first threshold and the indication related to the mobility of mobile terminals into/out of the area trespasses a second threshold.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a U.S. National Phase Application under 35 U.S.C. §371 ofInternational Application No. PCT/EP2007/064580 filed Dec. 27, 2010,which was published Under PCT Article 21(2), the entire contents ofwhich are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to methods and systems forestimating, monitoring and managing road traffic. More specifically, thepresent invention relates to a method and system for determining trafficjams based on information derived from a cellular Public Land Mobiletelephony Network (PLMN).

2. Description of the Related Art

The estimation, monitoring and management of road traffic are normallyaccomplished based on a count of the number of vehicles that passthrough one or more points of the monitored network of roads.

Vehicles counting methods are essentially of two types: manual countingmethods and automatic counting methods.

Manual vehicles counting methods provide that operators, staying at theprescribed monitoring points along the roads, visually count the passingvehicles.

Automatic vehicles counting methods provide for placing, on or withinthe road floor, detectors adapted to detect the passage of the vehicles.Different types of detectors can be used, the more common being:

-   -   rubber pipes closed at an end and connected to a membrane at the        other end; the passage of a vehicle over the pipe creates a        pressure thereinside that causes the membrane to flex,        determining the increase of a vehicles counter;    -   metal coils through which an electric current is made to flow        that produces an electromagnetic field; the passage of a vehicle        alters the electromagnetic field, and this event is detected        causing the increase of a vehicles counter;    -   television cameras connected to automatic image recognition        systems adapted to count the number of transiting vehicles.

The manual counting of the passing vehicles, requiring the continuouspresence of people at the road sections to be monitored, is used onlyfor time-limited monitoring campaigns.

On the contrary, automatic vehicles counting methods are used formonitoring the road traffic for relatively long periods of time;however, the deployment of the detectors on the roads network and theirconnection to a central data processing server is very expensive,especially in medium and large urban areas, which are the scenarioswhere the road traffic monitoring, estimation and management is moreuseful.

A known alternative to the above-described vehicles counting methodsmakes use of a certain number of vehicles (called “floating cars”)equipped with a GPS receiver which regularly transmit to a servicecenter its position and speed, thereby allowing the service center toestimate the road traffic.

This method is as well very expensive, and its effectiveness is closelyrelated to the number of circulating vehicles equipped with GPSreceivers, i.e. to the number of floating cars; due to this, continuousmonitoring of all the main roads of a certain area may not be possible.

In recent years, cellular PLMNs have also been used for the purposes ofestimation, monitoring and management of the road traffic, thanks to thewidespread presence of mobile phones among the population.

Systems that exploit cellular PLMNs for the estimation, monitoring andmanagement of the road traffic varies according to the type ofinformation on the position of the vehicles that they require for theiroperation.

For example, U.S. Pat. No. 5,465,289 discloses a system that makes useof sensors for monitoring communications going on in the cellular PLMN;number of calls placed, number of handovers performed, number ofemergency calls are thus extracted, from which the system derives, basedon a comparison of historical data, an estimation of the vehiclestraffic, particularly the number of circulating vehicles and the numberof accidents in a unit time.

In EP 763807 a method and system for detecting traffic jams aredescribed; a traffic jam in a certain road section is assessed when thePLMN traffic in the network cell covering that road section exceeds apredetermined threshold. The method also allows determining the drivingdirection experiencing the traffic jam: assuming that the PLMN trafficthreshold is exceeded firstly in a first network cell, and then in theadjacent, second network cell, located for example at the north of thefirst cell, it can be desumed that the driving direction experiencingthe traffic jam is that directed from the north to the south.

SUMMARY OF THE INVENTION

The Applicant has observed that known methods and systems do not providetotally satisfactory results when the estimation of traffic jams isconcerned.

In particular, concerning the solution disclosed in EP 763807, theApplicant has observed that, in practical cases, the two predeterminedthresholds are not exceeded at the same time in the two cells, rather inthe second cell the threshold is exceeded with a certain time delaycompared to the first cell, because it is necessary to wait for thevehicles queue in the considered road section to reach the second cell.Such a delay is higher the wider the network cells, thus, particularlyin extraurban areas (where the PLMN cells are usually wider compared tourban areas) it is difficult to quickly provide information about wherea traffic jam exists.

The Applicant has tackled the problem of providing an efficient serviceof detection of traffic jams on roads of a roads network, useful inparticular for vehicles drivers for avoiding to stay in queue.

In particular, the Applicant has tackled the problem of providing aservice that is capable of determining the driving direction that may beaffected by a traffic jam in a way that is not affected by the problemsof known methods.

The Applicant has found that a solution to these and other problems mayrely on the definition and use of two distinct thresholds: a firstthreshold related to the amount of call traffic successfully handled bya generic PLMN cell, and a second threshold related to the number ofhandovers successfully occurred between each PLMN cell towards any othercell adjacent thereto. The first threshold allows identifying the roadsection where a traffic jam is occurring, whereas the second thresholdallows identifying the driving direction on that road section.

In particular, the present invention exploits counters that count thehandled traffic handled by each cell of a generic BSC (Base StationController) or similar network apparatus of a cellular PLMN, and thenumber of handovers that took place between a generic cell and any otheradjacent cell. The values of these counters are compared topredetermined thresholds, for example determined by considering thecounter values over a sufficiently long time span, e.g. arithmeticallyaveraging the counter values over a time interval that may include apredetermined number of days preceding the current time instant.

At the output, an indication of the road sections experiencing a trafficjam is provided, together with the driving direction that is affected bythe traffic jam.

According to an aspect of the present invention, a method of estimatingtraffic jams on a roads network is provided, comprising:

-   -   receiving information from at least one cellular PLMN covering a        geographic region wherein at least one road of the roads network        to be monitored is located, wherein said information comprises        data related to a call traffic handled by the cellular PLMN in        an at least one area of said geographic region, and an        indication related to a mobility of mobile terminals into/out of        said area;    -   providing an indication of traffic jam in said at least one road        in case said call traffic handled by the cellular PLMN in the at        least one area exceeds a first threshold and the indication        related to the mobility of mobile terminals into/out of said        area trespasses a second threshold. Trespassing may mean either        exceeding or falling below.

Said providing the indication of traffic jam may comprise:

-   -   comparing the call traffic handled by the cellular PLMN in the        at least one area to the first threshold;    -   in case the call traffic handled by the cellular PLMN in the at        least one area exceeds the first threshold, comparing the        indication related to the mobility of mobile terminals into/out        of said area to the second threshold; and    -   providing the indication of traffic jam in at least one transit        direction along said road in case the mobility of mobile        terminals into/out of said area trespasses the second threshold.

The method may, further comprise calculating at least one among thefirst and second thresholds based on historical data related to the calltraffic handled by the cellular PLMN and, respectively, to theindications related to the mobility of mobile terminals, particularlycalculating averages of said historical data, and, possibly, determiningstandard deviations of a statistical distribution of said historicaldata.

Said at least one area may include at least one cell of the cellularPLMN, said data related to a call traffic handled by the cellular PLMNin the at least one area may include data related to a number of callshandled by said at least one cell, and said indication related to themobility of mobile terminals into/out of said area may include datarelated to a number of handovers having the at least one cell as asource or as a destination.

Said at least one cell may include a first cell and a second celladjacent to the first cell, and said providing an indication of trafficjam in said at least one road may include providing an indication of adriving direction on the road experiencing the traffic jam, saidproviding the indication of the driving direction may comprise:

-   -   indicating that the traffic jam is experienced in a first        driving direction if the number of handovers from the first cell        to the second cell trespasses the second threshold; and    -   indicating that the traffic jam is experienced in a second        driving direction if the number of handovers from the second        cell to the first cell trespasses the second threshold.

The method may further comprise subdividing the at least one road intoelementary road segments delimited by the boundary of the at least afirst and a second cell, and providing traffic jam indications for theelementary road segments.

According to another aspect of the present invention, a system forestimating traffic jams on a roads network is provided, adapted to:

-   -   receive information from at least one cellular PLMN covering a        geographic region wherein at least one road of the roads network        to be monitored is located, wherein said information comprises        data related to a call traffic handled by the cellular PLMN in        an at least one area of said geographic region, and an        indication related to a mobility of mobile terminals into/out of        said area;    -   provide an indication of traffic jam in said at least one road        in case said call traffic handled by the cellular PLMN in the at        least one area exceeds a first threshold and the indication        related to the mobility of mobile terminals into/out of said        area trespasses a second threshold.

For providing the indication of traffic jam the system may be adaptedto:

-   -   compare the call traffic handled by the cellular PLMN in the at        least one area to the first threshold;    -   in case the call traffic handled by the cellular PLMN in the at        least one area exceeds the first threshold, compare the        indication related to the mobility of mobile terminals into/out        of said area to the second threshold; and    -   provide the indication of traffic jam in at least one transit        direction along said road in case the mobility of mobile        terminals into/out of said area trespasses the second threshold.

The system may also be adapted to calculate at least one among the firstand second thresholds based on historical data related to the calltraffic handled by the cellular PLMN and, respectively, to theindications related to the mobility of mobile terminals. Said calculatemay comprise calculating averages of said historical data, and possiblydetermining standard deviations of a statistical distribution of saidhistorical data.

Said at least one area may include at least one cell of the cellularPLMN, said data related to a call traffic handled by the cellular PLMNin the at least one area may include data related to a number of callshandled by said at least one cell, and said indication related to themobility of mobile terminals into/out of said area may include datarelated to a number of handovers having the at least one cell as asource or as a destination.

Said at least one cell may include a first cell and a second celladjacent to the first cell, and the system may be adapted to provide anindication of a driving direction on the road experiencing the trafficjam, said provide the indication of the driving direction comprising:

-   -   indicating that the traffic jam is experienced in a first        driving direction if the number of handovers from the first cell        to the second cell trespasses the second threshold; and    -   indicating that the traffic jam is experienced in a second        driving direction if the number of handovers from the second        cell to the first cell trespasses the second threshold.

The system may be adapted to subdivide the at least one road intoelementary road segments delimited by the boundary of the at least afirst and a second cell, and to provide traffic jam indications for theelementary road segments.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the present invention will bemade clear by the following detailed description of an embodimentthereof, provided merely by way of non-limitative example, made withreference to the attached drawings, wherein:

FIG. 1 synthetically shows a part of a monitored roads network, and aportion of a cellular PLMN covering the area where the considered partof the roads network is located;

FIG. 2 schematically shows, in terms of functional blocks, a systemaccording to an embodiment of the present invention for detectingtraffic jams;

FIG. 3 shows, in tabular form, counters of the call traffic handled byPLMN cells under the responsibility of a BSC;

FIG. 4 shows, in tabular form, counters of handovers between the cells;

FIG. 5 shows, in tabular form, data identifying geographic areas coveredby the different PLMN cells;

FIG. 6 shows, in tabular form, data geographically identifying the roadsections;

FIG. 7 is a schematic flowchart of a method according to an embodimentof the present invention for calculating call traffic and number ofhandovers thresholds, to be used for the detection of traffic jams;

FIG. 8 shows, in tabular form, data regarding the call traffic in thedifferent PLMN cells, aggregated as a result of a step of the method ofFIG. 7;

FIG. 9 shows, in tabular for, data regarding the number of handoversbetween the cells, aggregated as a result of a step of the method ofFIG. 7;

FIG. 10 shows, in tabular form, handled traffic threshold valuescalculated as a result of a step of the method of FIG. 7;

FIG. 11 shows, in tabular form, number of handovers thresholdscalculated as a result of a step of the method of FIG. 7;

FIG. 12 exemplifies a way road sections are subdivided into elementscovered by single cells;

FIG. 13 is a table of start and stop coordinates of the different roadelements;

FIG. 14 is a schematic flowchart of a method according to an embodimentof the present invention for detecting traffic jams.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

Making reference to the drawings, in FIG. 1 a part of a monitored roadsnetwork is schematically depicted. The drawing also schematically showsa portion of a cellular PLMN network that covers the geographic areawhere the considered part of roads network is located. Hereinafter,merely by way of example, it will be assumed that the cellular PLMNnetwork is a GSM (Global System for Mobile communications) network,however it should be understood that the specific type of cellular PLMNis not limitative to the present invention, which also applies to othertypes of cellular PLMN networks, like for example UMTS (Universal MobileTelecommunications System) network or other third-generation networks.

In the drawing, reference numeral 105 denotes Base Transceiver Stations(BTSs) of the cellular PLMN; each BTS 105 covers (being the “bestserver” therein) a geographic area, called a “cell”, which in thedrawing is for simplicity depicted as hexagonal in shape. It should beunderstood that, in practical applications, the PLMN cells generally donot have an hexagonal shape, and different cells have different areacoverage (the shape and width of a generic cell depending on aspectslike for example the BTS's transmission power and the morphology of theterritory; for example, PLMN cells in urban area are typically smallerthan PLMN in extraurban area).

The BTSs 105 handles the physical communication with the mobileterminals in the respective cells.

The BTSs 105 are connected to respective Base Station Controllers (BSCs)110 through PLMN core network links 115, transporting the PLMN traffic(calls placed by mobile terminals located in the PLMN cells, SMS or MMSmessages, data traffic in case the PLMN network is connected to a GPRSinfrastructure, multicast-delivered contents) and signalling for theprotocols that allow the proper operation of the cellular PLMN (like forexample the signalling necessary for the handover procedures, whichensure the service continuity while the mobile terminals move across theterritory, and the location update procedures, which allow the PLMN tokeep track of the geographic macroarea (a geographic area correspondingto groups of network cells) where a generic mobile terminal is located).

The BSCs 110 manage the associated BTSs 105, routing the calls andmanaging the mobile terminals' mobility between different cells (i.e.,the handovers).

The BSCs 110 are connected to respective Mobile Switching Centers (MSCs)120, through links 125, which transport the PLMN traffic and signallingfor core network protocols.

The MSCs 120 manage the associated BSCs 110 and manage the set-up of thecalls and their routing through the network.

It is pointed out that, in case of PLMNs different from a GSM network,the Radio Access Network (RAN) structure, albeit similar, may beslightly different; for example, in the case of a UMTS network, the roleof the BTSs is played by so-called “Node-Bs”, which are connected toRadio Network Controllers (RNCs).

As schematically shown in the drawing, every BSC 110 has a localdatabase 130 where counter values of several different counters arestored, which a PLMN operator may inspect to assess the network status.In particular, in the database 130 counter values of the handled calltraffic, handled by the BTSs controlled by the BSC, and of the number ofhandovers involving the network cells managed by the BSC are stored.

Referring to FIG. 2, there is schematically shown a road section 205having two lanes 205-1 and 205-2 with opposite driving directions: fromright to left in lane 205-1, and from left to right in lane 205-2. Alsoshown are cells c0 to c5 of a cellular PLMN, for example the PLMN ofFIG. 1, and one BSC 110 managing the BTSs (not shown) of the cells c0 toc5, with the local database 130.

FIG. 3 schematically shows, in tabular form, a managed traffic counterof the generic BSC 110, stored in the local database 130. For every PLMNcell under the competence of that BSC, identified by the respective cellidentifier (table columns labeled C_Id, one column for each cell; thecell identifiers of the cells c0 to c5 are assumed to be c0, c1, c2, c3,c4 and c5), a plurality of traffic count values is stored (table columnsTr_Val, one column for each cell), each count value representing theamount of call traffic (phone calls, messages, data traffic etc.) thatthe respective cell was able to handle in a respective time internal ΔTstarting from a predetermined start time T₀ (in the table, the genericcall traffic count value being denoted Vij, where the index i denotesthe PLMN cell and the index j denotes the considered time interval).

FIG. 4 schematically shows, also in tabular form, a number of handoverscounter of the generic BSC 110, stored in the local database 130. Forevery PLMN cell under the competence of that BSC, identified by therespective cell identifier (table columns labeled S_C_Id, one column foreach cell; the cell identifiers of the cells c0 to c5 are assumed to bec0, c1, c2, c3, c4 and c5), the number of handovers (table columns HO#)occurring from the considered cell (regarded as the source cell) towardsany adjacent cell (the destination cell, table columns D_C_Id) in therespective time internals ΔT starting from a predetermined start time T₀are reported (in the table, the generic handover number is denotedNh_ij, where the index h denotes the considered time interval, the indexi denotes the source PLMN cell and the index j denotes the destinationPLMN cell). The BSC handover number counter may further keep track ofthe number of handovers from one cell managed by that BSC to cells thatare managed by different BSCs.

FIG. 2 also depicts schematically a system 210 according to anembodiment of the present invention for the detection of traffic jams onmonitored roads. The system 210 is shown in terms of functional blocks,each of which can be implemented by means of software, hardware, or as amix of hardware and software. Essentially, according to an embodiment ofthe present invention, the system 210 comprises a local database 215 anda processing and calculation engine 220. The system 210 is connected tothe BSCs 110 of the PLMN network (or at least to those BSC managing BTSsthat cover an area of interest, where the roads to be monitored arelocated). The system 210 has also access to a first external database225 storing data relating to all the BTSs 105 that cover the area wherethe road sections to be monitored are located, and other data useful tothe system 210. The system 210 has further access to a second externaldatabase 230 storing data related to the roads to be monitored.

The system 210 has an output 235 through which it provides to users(possibly comprising software applications) the indications aboutpossible traffic jams.

FIG. 5 schematically shows, in tabular form, a possible structure of thefirst external database 225, in an embodiment of the present invention.Each row of the table corresponds to a different BTS, whereas in thetable columns there are reported the unique identifier of the BTS (tablecolumn C_Id), its geographical position (table columns Lat and Long,standing for latitude and longitude), the number of vertexes of thegenerally irregular polygon defining the cell's borders (table columnN_vrtx), and the vertexes' geographic coordinates (table columnsCoord_1, Coord:2, . . . , Coor_m); the number of vertexes may andgenerally does vary from cell to cell.

FIG. 6 schematically shows, still in tabular form, a possible structureof the second external database 225, in an embodiment of the presentinvention. Each road to be monitored, identified by a respective roadidentifier (table column Rd_Id; the road identifiers are assumed to beRd1, Rd2, . . . , Rdm) can be subdivided into two or more road sectionsor segments, each one identified by a respective road segment identifier(table column Seg_Id). Of each road, or segment of road, the respectivestart and stop geographic coordinates are provided (table columnsStart_Coord (xstart, ystart) and Stop_Coord (xstop, ystop)). Thesequence of start and stop coordinates determines the orientation, i.e.the driving direction, on that road/segment of road. For example,considering the road section 205 in FIG. 2, points 205-A and 205-Bidentify two segments 205-1 and 205-2, the first segment having thestart coordinates corresponding to the coordinates of the point 205-Aand the stop coordinates corresponding to the coordinates of the point205-B, whereas the second segment has the start coordinatescorresponding to the coordinates of the point 205-B and the stopcoordinates corresponding to the coordinates of the point 205-A; thus,the driving direction is from point 205-A to point 205-B along the firstroad segment (205-1), whereas it is from the point 205-B to the point205-A along the second road segment (205-2).

Hereinafter, the operation of the system 210 according to an embodimentof the present invention will be described.

It is convenient, at least from the description viewpoint, divide thesystem operation into two phases: a start phase, and a normal operationphase.

Referring to the schematic flowchart of FIG. 7, in the start phase thesystem 210 performs, in an embodiment of the invention, the followingoperations.

Step 705—the system 210 reads the list of BTSs of the cellular PLMNscontained in the first external database 225.

Step 710—the system 210 reads, from the second external database 230,the list of roads (and respective road segments) to be monitored.

Step 715—the system 210 reads, from the local databases 130 of the BSCsof interest, the counter values of the traffic handled by the respectivenetwork cells in a predefined time range, defined for example by asystem administrator, and stores the read values in its database 215.

Step 720—the system 210 reads, from the local databases 130 of the BSCsof interest, the number of handovers in which the respective networkcells have been involved, in the predefined time range, and stores theread values in its database 215.

Step 725—The system 210 calculates, for every BTS covering the area ofinterest, respective handled traffic thresholds.

Step 730—The system 210 calculates, for every BTS of the area ofinterest, respective handover number thresholds for the handovers fromany cell towards any other adjacent cell.

Step 735—the system 210 subdivides the roads or road segments intoelementary road segments, based on the area coverage by the differentBTSs.

Step 740—the system identifies the PLMN cell towards which a handover isperformed when moving from one elementary road segment to the successiveone.

FIG. 8 schematically shows, in tabular form, the content of the sectionof the system database 215 devoted to store handled call trafficcounters after step 720. The start instant T0′ of the monitoring timerange does not in general coincide with the start instant T0 startingfrom which the BSCs stores, in their local databases 130, the calltraffic counter values—the instant T0 may be the time instant at whichthe BSC is turned on, or a subsequent time instant, from which the BSCstarts updating the traffic local database after having filled it. Thetime instant T0′ may instead be the current time minus the monitoringtime range (usually of the order of some months) set for example by thesystem administrator. The values reported in the table have the samemeaning as those reported in the table of FIG. 5.

FIG. 9 schematically shows, in tabular form, the content of the sectionof the system database 215 devoted to store handovers number countersafter step 725. The values reported in the table have the same meaningas those reported in the table of FIG. 6.

FIG. 10 schematically shows a table built as a result of step 725, inwhich, for every BTS (i.e., for every PLMN cell), identified by therespective cell identifier, a respective handled traffic thresholdTr_Tsch is stored, calculated for example by averaging the handledtraffic counter values, stored in the BTS local database, in the timerange of interest, set for example by the system administrator;alternatively, for every BTS, two or more handled traffic thresholds canbe calculated, each one related to a specific time interval ΔT (forexample, a specific time of the day, e.g. morning, afternoon, evening,night), calculated by averaging all the values of traffic handled by theBTS in the considered time range and in the specific time interval ΔT.

FIG. 11 schematically shows a table built as a result of step 730, inwhich, for every BTS (identified by the respective cell identifier)regarded as a source cell in a handover, all the possible destinationBTSs (adjacent cells) are listed (i.e., those BTS towards which ahandover originating from the source BTS occurred), together with thecorresponding thresholds of number of successful handovers. Also in thiscase, the thresholds can be calculated averaging all the handover valuesfrom the considered source BTS to the generic destination BTSs in theconsidered time range.

In step 735, every elementary road segment has two ends that coincidewith the points at which the roads or road segments to which theelementary road segment belongs intersects PLMN cells. For example,making reference to FIG. 12, along the road segment 205-1 threeelementary road segments 1203-1, 1203-2 and 1203-3 are defined, whereason the road segment 205-2 three road segments 1204-1, 1204-2 and 1204-3are defined. The points that delimit the elementary road segments arethe points 1205, 1206, 1207 and 1208, i.e. the points of intersectionbetween the road segments 205-1 and 205-2 and the PLMN cells c0, c2 andc5. The elementary road segments, similarly to the roads/road segments,have an orientation, thus, considering for example the elementary roadsegment 1203-1, the start coordinates thereof coincide with those of thepoint 1205, whereas the stop coordinates of the elementary road segment1203-1 are those of the point 1206. The result of this step isschematically depicted in FIG. 13, where a table is shown in which, forevery road and road segment, the constituent elementary road segmentsare listed, identified by an elementary road segment identifier (tablecolumn El_seg_Id), together with the respective start and stopcoordinates, and the identifier of the PLMN cell in whose coverage areathe elementary road segment is located. In case of roads having twodriving directions, two elementary segments of that road can be locatedin a same cell. In case of neighboring roads, like those convergingtowards a road crossing, a higher number of elementary road segments maybe located in a same cell.

In step 740, the system 210 identifies the PLMN cell towards which amobile terminal makes a handover when exiting a certain elementary roadsegment to enter the successive elementary road segment (having as startcoordinates the stop coordinates of the preceding elementary roadsegment). Such a PLMN cell may or may not coincide with the cellcovering the elementary road segment being exited. For example,referring to FIG. 12, and considering the elementary road segment1203-2, the cell towards which handover is made is the cell c2, whereasfor the elementary road segment 1204-2 the cell towards which handoveris made is the cell c5. The table shown in FIG. 13 is built as a resultof step 740. The identifier of the cell towards which handover is madeis inserted in the table column HO_C_Id. In case of a road having twodriving directions, or in the case of crossing roads, the indication ofthe cell towards which the handover is made will allow identifying thespecific elementary road segment where a traffic jam occurred, asdescribed in the following.

After the start phase, the system 210 enters a normal operation phase,which is schematized by the flowchart of FIG. 14. Essentially, at theend of every time interval ΔT0, the system 210, particularly theprocessing engine 215, performs, for every PLMN cell, the followingoperations:

Step 1405—the system 210 inquiries the local database 130 of the BSCcompetent for the generic cell ci under consideration, and reads thevalue of the handled traffic counter TSi for that cell.

Step 1410—The system 210 compares the read handled traffic counter valueTSi with the traffic threshold value Traffic_Th_i calculated for thatcell ci; at the first run, the threshold value is that calculated in thestart phase, as described above, and stored in the table of FIG. 10,whereas in subsequent runs the threshold value is that calculated in thepreceding run (as described later—step 1450).

Step 1415—In case the read value TSi exceeds the threshold Traffic_Th_i,(exit branch Y in the flowchart), the system 210 selects, from the tableshown in FIG. 13, all the elementary road segments covered by the cellci.

Step 1420—For all the elementary road segments thus selected, the system210 identifies the respective cells cj destination of a handover.

Step 1425—The system 210 reads, from the BSC local database, the valueof the number of successful handovers HOij from the cell ci towards allthe cells cj identified at the preceding step.

Step 1430—The system 210 compares the number of successful handoversvalues HOij with the handover number threshold values HO_Th_ijcalculated, for the first run, in the start phase, as described above,or, in each subsequent run, at the preceding run, and stored in thetable of FIG. 11.

In case for one or more of the possible handover destination cells, forexample for the destination cell cj, the number of successful handoversfrom the source cell ci to the destination cell cj is lower than therespective threshold HO_Th_ij (exit branch A in the flowchart), thesystem provides in output an indication of a traffic jam in theelementary road segment covered by the cell ci and having as handoverdestination cell the cell cj (step 1435).

In case for all the cells cj being a possible destination of handoversfrom the origin cell ci the number of successful handovers from the cellci to the handover destination cells is higher than the respectivethresholds (exit branch B in the flowchart), the system 210 provides inoutput the indication of traffic jam on all the elementary road segmentscovered by the cell ci, without providing an indication of thedirections along which the traffic jam is experienced (step 1440).

Step 1445—In case at step 1410 the system 210 assesses that the valueTSi is lower than the threshold Traffic_Th_i (exit branch N in theflowchart), the system 210 reads from the local database of the BSC thevalues of handled traffic and successful handovers for the cell ci notread at the preceding time interval, and stores them in the localdatabase 215, updating the tables in FIGS. 8 and 9.

Step 1450—The system recalculates the thresholds of handled traffic andhandover number for the cell ci, and updates the tables of FIGS. 10 and11.

This sequence of operations is repeated at the end of each time intervalΔT0.

The system according to the herein described embodiment of the inventioncan be implemented by means of any data processing system and with anyoperating system (Windows, Linux, Unix, MAC OS). The computer programsfor implementing the system of the present invention can be written inany programming language, such as the Ansi C++, which exhibits goodprogramming flexibility and guarantees high performance levels in termsof processing speed; other programming languages can however beexploited, like Java, Delphi, Visual Basic. The choice of the languageAnsi C++ is dictated by the.

As pointed out in the foregoing, the present invention is not limited toany specific PLMN network, which can for example be a second-generation(2G) network or a 3G network.

An advantage of the present invention is that no changes to theprotocols of the cellular PLMN are required, nor changes to the hardwareor the software of the mobile terminals.

The system of the present invention may communicate with the cellularPLMN apparatuses (e.g., the BSCs) by means of any communicationtechnology, which can for example be by wired or wireless or optical,exploiting point-to-point or point-to-multipoint connections.

The system may also receive data from two or more cellular PLMNs, run bya same or by different operators, exploiting similar or differentnetwork apparatuses.

The system of the present invention may have a centralized or adistributed architecture (for example, one system may be associated withevery BSC), the choice depending for example on the number of roads tobe monitored, on the transmission capacity of the communication linksbetween the system and the PLMN apparatuses, the storage capacity of thesystem database and the processing power of the processing engine.

The way in which the coverage of a geographic area by the PLMN iscalculated is not limitative for the present invention. For example, thePLMN area coverage may be provided by a PLMN planning tool, of the typeused by PLMN operators to plan PLMNs, or it can be obtained using anad-hoc tool, based for example on geometrical criteria, considering forexample a generic PLMN cell as the set of territory points close to acertain BTS.

The way in which handled call traffic thresholds and handover numbersthresholds are calculated is not limitative for the present invention;for example, as an alternative to what described in the foregoing, thethreshold may be calculated based on statistical parameters like thestandard deviation, or a multiple thereof, of all the counter values inthe time range of interest. The threshold could also be differentiatedbased on the time zone of the day (morning, afternoon, evening, night),on the day of the week, on the period of the year (season).

The time range in which the thresholds are calculated may be fixed orvariable, for example based on the hour of the day, of the month, of thetraffic load of the PLMN (number of users connected, handled traffic),based on the degree of confidence of the output that the systemadministrator wishes, based on the price the final user is available topay for enjoying the service, and the like.

The method and system of the present invention may also exploit othertypes of counters among those held by the network apparatuses, like theBSCs, for example the counter of net number of successful handovers ineach cell (given by the difference between the outgoing handovers andthe ingoing handovers), the counter of the number of “Location Updates”(the results of the GSM network procedures that allow the networkgaining knowledge of the macroarea where the mobile terminals arelocated, which correspond to the “Routing Area Update” procedures ofUMTS networks) in entrance/exit/net related to a macroarea, the counterof the number of “Routing Area Updates” in entrance/exit/net related toa macroarea, the counter of the number of unsuccessful calls originatedby the mobile terminals, and the like. These counters may also becombined together: for example, it may be possible to consider the sumof number of handovers in entrance to a cell and of the number ofhandovers in exit from that cell to any other cell). In general, theindication of traffic jam may be given in case the calculated thresholdis trespassed, and, depending on the specific counter used, thethreshold trespassing may correspond to exceeding the threshold orfalling below it.

More generally, the present invention has been here described presentingsome possible embodiments thereof, but those skilled in the art willreadily appreciate that several modifications to the describedembodiments are possible, as well as other possible embodiments, whichdo not depart from the scope of the protection as defined in theappended claims.

The invention claimed is:
 1. A method of estimating traffic jams on aroads network, comprising: receiving information from at least onecellular network covering a geographic region wherein at least one roadof the roads network to be monitored is located, wherein saidinformation comprises data related to call traffic handled by thecellular network in an at least one area of said geographic region, andan indication related to mobility of mobile terminals into/out of saidarea; providing an indication of traffic jam in said at least one roadin a case that said call traffic handled by the cellular network in theat least one area exceeds a first threshold and the indication relatedto the mobility of mobile terminals into/out of said area trespasses asecond threshold, wherein said providing the indication of traffic jamcomprises: comparing the call traffic handled by the cellular network inthe at least one area to the first threshold; in a case that the calltraffic handled by the cellular network in the at least one area exceedsthe first threshold, comparing the indication related to the mobility ofmobile terminals into/out of said area to the second threshold; andproviding the indication of traffic jam in at least one transitdirection along said road in a case that the mobility of mobileterminals into/out of said area trespasses the second threshold; andcalculating at least one among the first and second thresholds based onhistorical data related to the call traffic handled by the cellularnetwork and, respectively, to the indications related to the mobility ofmobile terminals, wherein the calculating comprises calculating averagesof the historical data.
 2. A method of estimating traffic jams on aroads network, comprising: receiving information from at least onecellular network covering a geographic region wherein at least one roadof the roads network to be monitored is located, wherein saidinformation comprises data related to call traffic handled by thecellular network in an at least one area of said geographic region, andan indication related to mobility of mobile terminals into/out of saidarea; providing an indication of traffic jam in said at least one roadin a case that said call traffic handled by the cellular network in theat least one area exceeds a first threshold and the indication relatedto the mobility of mobile terminals into/out of said area trespasses asecond threshold; and calculating at least one of the first and secondthresholds based on historical data related to the call traffic handledby the cellular network, wherein said calculating comprises determiningstandard deviations of a statistical distribution of said historicaldata.
 3. The method of claim 1, wherein said at least one area includesat least one cell of the cellular network, said data related to calltraffic handled by the cellular network in the at least one area includedata related to a number of calls handled by said at least one cell, andsaid indication related to the mobility of mobile terminals into/out ofsaid area include data related to a number of handovers having the atleast one cell as a source or as a destination.
 4. The method of claim3, wherein said at least one cell includes a first cell and a secondcell adjacent to the first cell, and wherein said providing theindication of traffic jam in said at least one road includes providingan indication of a driving direction on the road experiencing thetraffic jam, said providing the indication of the driving directioncomprising: indicating that the traffic jam exists in a first drivingdirection if the number of handovers from the first cell to the secondcell trespasses the second threshold; and indicating that the trafficjam exists in a second driving direction if the number of handovers fromthe second cell to the first cell trespasses the second threshold. 5.The method of claim 4, further comprising subdividing the at least oneroad into elementary road segments delimited by the boundary of at leastthe first cell and the second cell, and providing traffic jamindications for the elementary road segments.
 6. A computer system forestimating traffic jams on a roads network, configured to: receiveinformation from at least one cellular network covering a geographicregion wherein at least one road of the roads network to be monitored islocated, wherein said information comprises data related to call traffichandled by the cellular network in an at least one area of saidgeographic region, and an indication related to mobility of mobileterminals into/out of said area; provide an indication of traffic jam insaid at least one road in a case that said call traffic handled by thecellular network in the at least one area exceeds a first threshold andthe indication related to the mobility of mobile terminals into/out ofsaid area trespasses a second threshold, wherein for providing theindication of traffic jam the system is configured to: compare the calltraffic handled by the cellular network in the at least one area to thefirst threshold; in a case that the call traffic handled by the cellularnetwork in the at least one area exceeds the first threshold, comparethe indication related to the mobility of mobile terminals into/out ofsaid area to the second threshold; and provide the indication of trafficjam in at least one transit direction along said road in a case that themobility of mobile terminals into/out of said area trespasses the secondthreshold; and calculate at least one among the first and secondthresholds based on historical data related to the call traffic handledby the cellular network and, respectively, to the indications related tothe mobility of mobile terminals, wherein the calculate comprisescalculating averages of the historical data.
 7. The system of claim 6,wherein said calculate comprises determining standard deviations of astatistical distribution of said historical data.
 8. The system of claim6, wherein said at least one area includes at least one cell of thecellular network, said data related to call traffic handled by thecellular network in the at least one area include data related to anumber of calls handled by said at least one cell, and said indicationrelated to the mobility of mobile terminals into/out of said areainclude data related to a number of handovers having the at least onecell as a source or as a destination.
 9. The system of claim 8, whereinsaid at least one cell includes a first cell and a second cell adjacentto the first cell, and wherein the system is configured to provide anindication of a driving direction on the road experiencing the trafficjam, said provide the indication of the driving direction comprising:indicating that the traffic jam exists in a first driving direction ifthe number of handovers from the first cell to the second celltrespasses the second threshold; and indicating that the traffic jamexists in a second driving direction if the number of handovers from thesecond cell to the first cell trespasses the second threshold.
 10. Thesystem of claim 9, configured to subdivide the at least one road intoelementary road segments delimited by the boundary of at least the firstcell and the second cell, and to provide traffic jam indications for theelementary road segments.
 11. The method of claim 2, wherein saidproviding the indication of traffic jam comprises: comparing the calltraffic handled by the cellular network in the at least one area to thefirst threshold; in a case that the call traffic handled by the cellularnetwork in the at least one area exceeds the first threshold, comparingthe indication related to the mobility of mobile terminals into/out ofsaid area to the second threshold; and providing the indication oftraffic jam in at least one transit direction along said road in a casethat the mobility of mobile terminals into/out of said area trespassesthe second threshold.
 12. The method of claim 2, wherein said at leastone area includes at least one cell of the cellular network, said datarelated to call traffic handled by the cellular network in the at leastone area include data related to a number of calls handled by said atleast one cell, and said indication related to the mobility of mobileterminals into/out of said area include data related to a number ofhandovers having the at least one cell as a source or as a destination.13. The method of claim 12, wherein said at least one cell includes afirst cell and a second cell adjacent to the first cell, and whereinsaid providing the indication of traffic jam in said at least one roadincludes providing an indication of a driving direction on the roadexperiencing the traffic jam, said providing the indication of thedriving direction comprising: indicating that the traffic jam exists ina first driving direction if the number of handovers from the first cellto the second cell trespasses the second threshold; and indicating thatthe traffic jam exists in a second driving direction if the number ofhandovers from the second cell to the first cell trespasses the secondthreshold.
 14. The method of claim 13, further comprising subdividingthe at least one road into elementary road segments delimited by theboundary of at least the first cell and the second cell, and providingtraffic jam indications for the elementary road segments.